For example, as a method for treating a cataract, a treatment method is known in which a clouded crystalline lens of a patient is extracted and then an intraocular lens is mounted in the eye of the patient. When an intraocular lens is used in place of a crystalline lens the focus of which is adjustable by relaxation/contraction of ciliary muscle in the eye, it is an important issue how a visual target is brought into focus by the intraocular lens. Patent Document 1 discloses an intraocular lens that focuses on a visual target by using movement of an anterior capsule and a posterior capsule that are left when a crystalline lens is extracted and that move in response to relaxation/contraction of ciliary muscle.